In communication techniques such as a Long-Term Evolution (-Advanced) technique, there is a method for changing a base station which communicates with a communication terminal. Generally, in base station handover, it needs to disconnect the connection between a communication terminal and the original base station (i.e., the source base station) and to establish a connection with a new base station (i.e., destination base station). Of course, there is also a technique of soft handing over the communication terminal in the prior art, wherein the communication terminal temporarily connects with two base stations in the handover, and disconnects the connection with the source base station after establishing a stable communication with the destination base station, thereby achieving a seamless handover technique.